1. TECHNICAL FIELD OF THE INVENTION
The present invention relates in general to mine roof supports and, more particularly, to a shield-type support which employs an hydraulic piston and cylinder unit as an adjustment device between the pivotably-interconnected goaf shield and roof-engaging structure thereof.
2. DESCRIPTION OF PRIOR ART
In conventional shield-type supports of the aforementioned kind and of low structural height or low extension height, the bearing or mounting for the cylinder of the unit on the inside of the goaf shield is largely inaccessible or is only accessible with difficulty so that assembly and dismantling of the unit is difficult. To overcome this problem it is known from German patent specification P34 05 888 to mount an intermediate tube segment on the shield by means of a hinge pin. The tube segment has a socket into which the cylinder can be located as a plug-in joint. The segment partially surrounds the cylinder of the unit and has open recesses for receiving journals on the peripheral wall of the cylinder. With this known arrangement, the cylinder is largely resistant to tensile and compressive forces but is supported for mobility on the shield. The tube segment, which has a length approximately equal to the cylinder of the unit, provides a force transmitting component and allows simple and rapid assembly and disassembly of the unit even if the mounting on the shield is inaccessible. The cylinder can be introduced into the socket of the tube segment and its journals fitted into the reception recesses at all times. The connection joint between the piston rod of the unit and the roof-engaging structure is also accessible at all times and once the cylinder has been released the piston rod joint can be disconnected to free the entire unit. This known arrangement suffers from the disadvantage that the tube segment is bulky and heavy and the location of the journals is not particularly efficient or free from problems.
A general object of the present invention is to provide an improved mounting means for the cylinder of the adjustment unit.